Juniper Networks, Inc. Juniper Networks, Inc. This document specifies a mechanism, referred to as "Intent Driven Service Mapping", that uses BGP to express intent based association of overlay routes, with underlay routes having specific Traffic Engineering (TE) characteristics, that satisfy a certain Service Level Agreement (SLA). The document achieves this by defining new constructs, to group underlay routes with sufficienty similar TE characteristics into identifiable classes (Transport Class), that overlay routes use as an ordered set to resolve reachability (Resolution Scheme) towards service endpoints. These constructs can be used to realize the "IETF Network Slice" defined in TEAS Network Slices framework. This document specifies protocol procedures for BGP that enable dissemination of such service mapping information in a network that may span multiple cooperating administrative domains. These domains may be administered either by the same provider or by closely coordinating providers. A new BGP address family that leverages RFC-4364 procedures and follows RFC-8277 NLRI encoding, is defined to advertise underlay routes with its identified class. This new address family is called "BGP Classful Transport", a.k.a., BGP CT.